The purpose of a bellows sealing member of the above type is to seal off the opening - which must be relatively large on account of the necessary piston rod movement - in the end wall of the diaphragm cylinder for accommodating the piston rod movement, in such a manner that the spring chamber and the members of the diaphragm cylinder located therein are protected against entry of foreign materials and other impurities therein caused by splashing water, dirt thrown up by the vehicle wheels or other, similarly aggressive elements. There are known bellows type sealing members presently whose ends are each provided with a torus, by which one end of the bellows can be fastened to a support member coaxially fixed in the piston rod opening of the diaphragm cylinder, and the other end can be pulled over the piston rod and attached thereto for instance by means of a clamp. This is disadvantageous, however, since, in order to mount the bellows, either the forkhead has to be removed from the piston rod or the bellows has to be slit at the end secured to the piston rod, thus causing a leak. A further disadvantage would occur with a piston rod having a non-detachable forkhead, so that the opening in the upper part of the diaphragm cylinder for the piston rod passage is irregular rather than round and, therefore, cannot be sufficiently covered by the torus.